1. Related Field
The invention relates to three-dimensional imaging of physical objects. In particular, the invention relates to intra-oral (in vivo) laser imaging of dental items including dentition, prepared dentition, impression materials and the like.
2. Description of the Related Art
A three-dimensional (“3D”) visual image of a physical object may be generated by a computer that processes data representing shapes, surfaces, contours and/or characteristics of the object. The data is generated by optically scanning the object and detecting or capturing the light reflected from the object. Principles such as Moiré, interferometry, and laser triangulation, may be used to model the shape, surfaces, contours and/or characteristics of the object. The computer displays the 3D image on a screen, or computer monitor.
Existing intra-oral 3D imaging systems use a variation of the Moiré imaging technique. Such systems use structured white light to project a two-dimensional (“2D”) depiction on the object to be imaged. Moiré systems use the 2D lateral information, and input from skilled operators, to determine relative dimensions of adjacent features. Moiré systems also use a sinusoidal intensity pattern that is observed from a position other than a projection angle that does not appear sinusoidal. Therefore, an inferred point-by-point phase angle between an observed and a projected image may be correlated to height data.
Intra-oral dental imaging systems, based on the Moiré technique image a dental item, such as a tooth, directly from or below occlusal surfaces of the tooth. Such systems have low depth resolution and may not accurately image or represent a surface that is undercut or shadowed. Intra-oral dental imaging systems also may require a powder or the like to provide a uniform color and reflectivity required by limitations of the white light techniques. The powder layer may increase or introduce errors in the digitized data, due to non-uniformity of the powder thickness.